I would say one of the most interesting teachers I have met would be the late Akira Tohei, Midwest Regional Head of the USAF in Chicago. He was one of O'Sensei's students. Very short, but had very effective techniques. He had an intensity about him I had never seen before. He would look at you and it felt like you were shrinking sometimes. As time went on, I got to know more about him and he was an excellent teacher. He is truly missed.